1. Field of the Invention
The present invention relates to devices used in surgical and medical treatment practices, and particularly to a skull clamp device for immobilizing the skull. The device is particularly useful in immobilizing the skull during neurosurgical procedures while providing a sensor safety system for limiting the pressure exerted on the skull by the clamp and providing an alert to the medical team of any potentially hazardous application of clamp pressure or any loosening or slippage of the skull clamp device.
2. Description of the Related Art
There are many medical situations in which it is absolutely vital to immobilize the head of a patient receiving treatment. One common example is during neurosurgery or other cranial surgery, during which the head of the patient must be completely immobilized due to the extremely delicate nature of the operation. Another example is when a neck injury patient is placed in traction to immobilize and protect the patient from further injury while promoting healing.
Various devices for immobilizing the skull have been developed in the past. A well-known example of such a device is the Mayfield® skull clamp that is often used during neurosurgery. This device includes a pair of contact points extending inwardly from an articulating frame on one side of the device, with a third adjustable contact point extending inwardly from the opposite side. The contact points are sharpened pins that penetrate the flesh and engage the outer layer of bone of the skull, and when properly positioned serve to absolutely immobilize the skull relative to the clamp. The clamp itself is adjustably mounted with secure position locking elements on to the structure of an operating table or other patient support structure, thereby absolutely immobilizing the head of the patient during the surgical procedure.
The above-described device is exemplary of other conventionally used cranial immobilizing devices that are well known in the art. These early cranial immobilizing devices present various problems, with one obviously being the potential hazard of manually over-tightening the clamp on to the skull of the patient. This conventional practice of the surgeon manually tightening the skull clamp on to the skull of a patient with the amount of pressure exerted by the clamp pins against the skull being controlled only by the tactile feedback sensed by the surgeon is potentially very dangerous. In many instances the surgeon or other medical practitioner might unintentionally apply too much pressure to the skull as he or she manually tightens the threaded adjustment screw(s) to drive the pin(s) into the bone resulting in an unintentional fracture of the bone. It is critical that the pins be set sufficiently deeply into the outer layer of the bone to completely immobilize the skull for neurosurgery and other cranial procedures without overstressing the bone and causing a skull fracture. The difference between the tactile feedback from applying too little pressure or too much pressure in securing the pins to the skull can be exceedingly small in certain instances. The amount of pressure applied in securing the pins into the outer layer of the skull is complicated by the wide diversity in bone thickness for different patients and even more so by the varied perception of pin pressure against the skull as sensed by individual surgeons during the exertion of manually operation of the clamping devices. Thus, the success of the procedure is completely dependent upon the individual skill level of the surgeon who must manually apply a sufficient but safe amount of penetrating pressure of the pins against the outer layer of the skull. A misjudgment about the amount of pressure to apply in driving the pins into the outer layer of the bone can easily result in a skull fracture, which creates an unnecessary hazard for the patient.
It often occurs that the pins may seem initially to be correctly set and secured into the outer portion of the bone; however, during the course of the surgery some slippage of the pins from their initial position on the skull may occur. When slippage of the connection of the pin to the skull does occur, the skull might move slightly with potentially disastrous results.
There is therefore a need for a skull clamp that can be attached to a patient with improved safety and reliability having an automated capability to control the penetrating pressure of the pin against the skull and a sensor/alarm system that if necessary can instantaneously stop the pin penetration into the skull while alerting the surgeon. A need exists for a skull clamp that is also capable of initiating an alarm if a properly set pin later slips from its position in the bone. Thus a skull clamp system with pressure limiting and alarm systems solving the aforementioned problems is desired.